42 PROCEEDINGS OF THE NATIONAL MUSEUM vor.. 7(i 



Genus OSTHIMOSIA JuUien, 1888 



OSTHIMOSIA ANATINA, new species 



Plate 7, Figures 4-8 



Description. — The zoarium is free, ramose, with branches rather 

 regularly cylindrical or compressed. The zooecia are irregularly 

 erect and oriented. The frontal is smooth or very slightly granulose, 

 surrounded by areolar pores. The aperture is terminal, suborbicular, 

 very little elongated; the rimule is wide, rounded, shallow, and is 



partially hidden by a large 

 very salient avicularian 

 umbo with semicircular 

 mandible. The ovicell is 

 large, globular, perforated 

 by large pores arranged in 

 quincunx, not closed by the 

 D operculum. The interzooe- 



FiGDRB 9. — OSTHIMOSIA ANATINA^ NEW SPECIES. .4, clal aviculaHa arc lar^e 



Operculum, X 85, with its two small muscu- ^• i. i "i-u ^ I 



LAR attachments, b-d, MANDIBLES, X 85, B, OF long, salieut, oval, without 

 A small inteezooecial avicularium, c, of an pivot with two condyles for 



ABNORMAL INTERZOOECIAL AVICULARIUM; AND Z), , ' A i^' -P +1 A' 



OP AN INTERZOOECIAL AvicDLARiuM WITH DUCK- tiie rotatiou 01 tue mancli- 

 BiLL FORM Ijle ; the orifice is formed by 



a narrow, elongated, oval proximal ope sium and a very much en- 

 larged distal calcified area; the mandible is large with duck-bill form. 

 The umbo of the deep zooecia projects between the superficial zooecia 

 in the form of small cylindrical, avicularian tubes. 

 Measuretnents. — 



[/ia=0.16 mm. [Za'y = 0.60 mm. 



Aperturaj^^^O ;L4 mm. ^arge avicularia|^^^_Q30 j,,n,. 



A-fJinities. — The interzooecial avicularia ai'e large or small; our 

 measurements are the maximum and are those of the avicularian 

 chamber itself and not that of the orifice. 



The avicularian beak measures 0.50 by 0.20 mm. on the well-pre- 

 served specimens. It much resembles in this feature, as also in the 

 fr'ontal, with areolar pores, Cellepora eatoniensis Busk, 1881. Os- 

 thimosia anatina differs in its perforated ovicells (and not smooth 

 according to Waters, 1904). It differs again from Cellepora cylin- 

 driformis Busk, 1884, from the Cape of Good Hope and from Aus- 

 tralia, which it resembles very much in its avicularium and its per- 

 forated ovicell, by the presence of areolar pores. The areolar pores 

 not only are hidden by the ectocyst, but they are not visible on the 

 incompletely calcified living specimens. A single specimen j)re- 

 served the base which is orbicular and little expanded. The sub- 

 stratum is unknown. 



